8.1 Battery Protector, Monitor, or Gauge?

Lithium ion batteries have high energy density and long cycle life. They also lack the memory effect of some other technologies. These characteristics make them attractive for portable electronic systems, but lithium ion batteries need to be operated within specified limits to be used safely. So batteries will include battery electronics to provide a signal to the system or to respond directly if these limits are exceeded.
What kind of information is used by the electronics to make decisions? Well, voltage, current, and temperature and how they change over time-- the electronics need to sense the required combination of those parameters to make a response. The response may be a signal or communication with the system, a switch to prevent charge or discharge, or in some cases, it may open a fuse.
The type of battery electronics needed varies depending on the type of battery pack. For simple packs, a simple protector may be all that is needed. This can range from a basic over-voltage protector to a more advanced protector that responds to under-voltage, temperature faults, or current faults.
Many advanced battery packs used in higher cell count batteries may require a battery monitor. A battery monitor measures individual cell voltages, battery current, and temperature, and reports these values to a controller. This information can be used by the system to adjust performance accordingly.
For example, the system could use this information to reduce the operating current if the temperature is too high. Battery monitors may also provide a cell balancing feature that can extend battery run time and also extend the lifetime of the battery. Monitors also include protections available that protect our ICs, but with much higher configurability.
For other advanced battery packs, a gauge IC may be used, which includes the features of the battery monitor, integrated with a controller that provides advanced gauging algorithms. Gauge ICs report the remaining capacity, runtime, and state of charge of the battery. Protections may be enhanced even further with software-based protections. A black box feature helps to diagnose battery packs that failed in the field, as well as many other features.
So which electronics should be used for a given system? Protectors offer the lowest complexity for simple pack designs. Monitors offer the highest flexibility. The pack designer is able to write code specific to their system needs, and this is often important where the system needs are unique. Gauge ICs offer the highest level of integration. They offer high accuracy state of charge information and faster development time since firmware is included, but they might limit flexibility.
Here is an example solution using the BQ769x0 battery monitor. This monitor family has devices for 5 cell, 10 cell, and 15 cell batteries. The monitor continuously measures the battery cell voltages, the temperature, and the current through the sense resistor, and reports this information to the microcontroller. It also provides multiple configurable hardware protections and will open charge and discharge FETs as needed to respond to fault conditions.
The microcontroller can make decisions based on the information provided by the monitor. It can also enable and disable the FETs, control the cell balancing feature, and can even do some basic gas gauging based on the voltage, current, and temperature information.
Here's a second example of a slightly more advanced battery pack. Here we see the same monitor family, working with the BQ78350 companion controller. The BQ78350 comes equipped with firmware designed to work directly with the BQ769x0 digital monitor, helping to accelerate product development. It also has fuel gauging and state of health reporting, as well as many of the other advanced features commonly included in TI fuel gauges, such as lifetime data logging and black box recording.
Many systems require the redundancy of a secondary protector for over-voltage. This example features the BQ7718 stackable over-voltage protector that can directly open the fuse if the primary protector was to fail.
Some systems may require the use of high side FETs. High-side FETs allow for continuous communication to the pack, regardless of whether the FETs are on or off. This allows the system to read critical pat parameters, despite safety faults, enabling the system to assess pack conditions before allowing operations to resume. The BQ76200 high-side in FET driver can be used with the BQ769x0 monitor and systems where high-side FETs are needed.
To learn more about our battery protectors, battery monitors, or fuel gauges, click on any of these links to take you to the product pages. Thank you for watching. 锂离子电池具有 高能量密度和 较长续航时间。 另外，相比其他一些技术， 锂离子电池不具有记忆效应。 这些特性使得 锂离子电池非常适合 便携式电子系统， 但锂离子电池 需要在额定 限值内工作， 以保证使用安全。 因此电池内会包含 电池电子装置， 以便在超出限值时 向系统发出信号 或直接进行响应。 该电子装置根据 哪些类型的信息 来作出决定呢？ 电压、电流 和温度 及其随时间变化的情况 -- 该电子装置需要检测 所需的参数组合 以作出响应。 此类响应可以是 向系统发送信号， 或是与系统进行通信，亦或是进行 一次开关以防止充电或放电， 而在某些情况下， 甚至可以断开保险丝。 根据电池组 类型的不同， 所需的电池电子装置 类型也各异。 对于简单电池组， 一个简单保护器 即可满足所有需求。 电子装置可以是 基本过压保护器， 也可以是能够 对欠压、温度故障 或电流故障 进行响应的 更高级保护器。 很多在更高节数的电池中 所使用的高级电池组 可能需要电池监控器。 电池监控器可测量 单节电池的电压、 电池电流 和温度， 并将这些数值 报告给控制器。 系统可使用 此类信息 对性能进行 相应调整。 例如，系统 可使用此类信息 在温度过高时 降低工作电流。 电池监控器还可 提供电池平衡功能， 该功能可延长 电池运行时间 并且延长 电池寿命。 监控器还包含 可用的 IC 保护功能， 但是其可配置性 远高于其他电子设备。 对于其他高级电池组， 可使用测量仪表 IC， 该测量仪表 IC 包含 电池监控器的功能， 并集成了可提供 高级监测算法的 控制器。 测量仪表 IC 可报告电池的 剩余时间、运行时间和 充电状态。 利用基于软件的 保护，可以进一步 增强保护功能。 黑盒功能以及 很多其他功能 有助于对发生 故障的电池组 进行现场诊断。 那么对于给定系统， 应使用哪些电子装置？ 保护器可使简单 电池组设计的 复杂性降至最低。 监控器可使电池组 设计的灵活性达到最高。 电池组设计人员 能够编写专门符合 其系统需求的代码， 当系统需要较为独特时， 这种能力通常十分重要。 测量仪表 IC 可使电池组 设计的集成程度达到最高。 可提供高精度 充电状态信息， 由于包含固件， 还可加快开发速度， 但是灵活性 可能会受限。 以下是使用 BQ769x0 电池监控器的一个示例 解决方案。 此监控器系列具有 5 节电池、10 节电池 和 15 节电池的器件。 该监控器通过 感应电阻器 持续测量电池电压、 温度和电流， 并将此类信息 报告给 微控制器。 该监控器还提供了 多种可配置硬件保护， 并可根据需要打开 充电和放电 FET， 从而对故障状况 作出响应。 微控制器能够根据 监控器提供的信息 作出决策， 还能根据电压、 电流和温度信息， 启用和禁用 FET， 控制电池平衡功能， 甚至进行一些 基本的电量监测。 以下是另一个关于 稍高级电池组的 示例。 此处的监控器 系列与此前相同， 采用了 BQ78350 配套控制器。 BQ78350 配备了 用于直接与 BQ769x0 数字监控器 搭配使用的固件， 有助于加速 产品开发。 该器件还具有电量监测和 健康状态报告功能， 以及 TI 电量监测通常包含的 许多其他高级功能， 例如使用寿命数据记录 和黑盒记录功能。 很多系统需要 次级过压保护器 作为冗余。 BQ7718 可堆叠过压保护器 就是一个这样的示例， 该保护器可在初级保护器 发生故障的情况下， 直接断开 保险丝。 一些系统可能需要 使用高侧 FET。 高侧 FET 可实现与 电池组的持续通信， 无论 FET 开启 或关闭，皆是如此。 这样即使发生系统故障， 系统仍可以读取 关键的模式参数， 因此可以 先评估电池组状况， 然后再恢复运行。 FET 驱动器中的 BQ76200 高侧 可与 BQ769x0 监控器和 需要高侧 FET 的系统 搭配使用。 要详细了解我们的 电池保护器、 电池监控器或 电量监测计， 请点击任一链接， 跳转至产品页面。 谢谢观看。

Description

March 6, 2019

If you are not sure if you should pick battery protector, monitor, gauge or several of those, this video is for you. This short overview provides a short summary of system requirements to help you choose.